I'm not doing anything but web browsing with Firefox, yet my MacBook Pro (ca. mid-2012) is very hot. I have 8GB of RAM so it's not a problem. There is about 5GB available at the moment. I tried a couple of solutions but they haven't worked. This is pretty annoying as I continue to have problems with 18.04.
user1@ubuntu:~$ cat /sys/class/thermal/thermal_zone*/temp
The MacBook Pro has an Intel Core i5 running at 2.5 GHz, 8GB RAM, a 500 GB SSD, and uses Intel HD Graphics with 1.5GB RAM.
lshw -c video | grep configuration shows
configuration: driver=i915 latency=0
lspci | grep VGA shows
00:02.0 VGA compatible controller: Intel Corporation 3rd Gen Core processor Graphics Controller (rev 09)
lspci -k | grep -EA3 'VGA|3D|Display' shows
00:02.0 VGA compatible controller: Intel Corporation 3rd Gen Core processor Graphics Controller (rev 09) Subsystem: Apple Inc. 3rd Gen Core processor Graphics Controller Kernel driver in use: i915 Kernel modules: i915